This invention relates generally to ventilation systems and, more specifically, to an improved ventilation system for an absorption refrigerator located within the interior of a recreational vehicle.
It is common for recreational vehicles to have refrigerators on board for cooling and preserving food and drinks in a compartment. These refrigerators are usually absorption-type refrigerators which use a heat source to effect refrigeration. An absorption refrigerator has a heat generator which heats a solution of a refrigerant and an absorbent. The heat releases the refrigerant from the absorbent to form a high pressure refrigerant vapor. The refrigerant vapor is condensed in a cooling condenser. Low pressure solution from the heat generator is sprayed on the refrigerant vapor in an absorber to absorb the vapor. The absorption causes the pressure of the vapor to be reduced, thereby causing evaporation in an evaporator between the condenser and the absorber. The refrigerant vapor expands in the evaporator which causes a temperature drop in the refrigerant which is used to cool the compartment. The solution of refrigerant and absorbent is then pumped back to the heat generator.
Absorption refrigerators are favored in vehicles, such as campers or recreational vehicles, because a compressor is not required and the heat generator can be an electrical resistance heater or a gas heater. The electrical resistance heater can be powered by a direct current supply of the vehicle or a commercial alternating current supply such as those available at campgrounds. The gas heater can be fueled by propane gas which is usually carried on recreational vehicles. Combustion of the propane creates waste gasses, such as carbon dioxide, which should be vented outside the vehicle.
It is typically necessary to cool the condenser and absorber of the refrigerator. This is economically achieved by creating a "natural draft" airflow over the condenser and absorber. To create this airflow, a duct is provided with intake vent in a side wall or floor and an exhaust vent in the ceiling to permit airflow over the condenser and absorber. In some installations, a fan is provided to create a "forced draft" airflow. Such fans run continuously and are a significant drain on available power.
One such installation is in recreational vehicles which are provided with a retractable structure usually referred to as a "slide-out" portion or room. The slide-out portion enables the recreational vehicle to have an exterior width which meets road restrictions during transportation a width which provides a comfortable interior layout during use. See U.S. Pat. No. 4,500,132 for an example of a recreational vehicle with a slide-out portion. When a refrigerator is located in the slide-out room the duct must move along with the slide-out room and a roof-top exhaust vent cannot be used.
Accordingly, there is a need in the art for an improved ventilation system for an absorption-type refrigerator which can be placed at any location in the recreational vehicle, including slide-out rooms, to increase the flexibility of floor plan designing. Airflow over the condenser and absorber should be facilitated by the ventilation system while conserving power. Air used to cool the condenser and absorber should come from outside the vehicle and be exhausted to carry heat and combustion products outside the vehicle.